1. Field of the Invention
The present invention relates generally to a pulley, and more particularly, to a self-camming or self rope-locking pulley.
2. Description of Related Art
Pulleys are generally known in the art. A pulley is a wheel or sheave with a groove along its edge for holding a line, such as a rope, cable, cord, or chain. A pulley may be used in a number of configurations. One such configuration is the block and tackle arrangement in which two pulleys work in unison, one pulley being fixed and another moving with the load. The simplest of pulleys includes a sheave or sheaves that all freewheel in both clockwise and counter-clockwise directions. More sophisticated pulleys provide locking mechanisms so that a load is locked in place when a force on a line carried by the sheaves is released. Such locking sheave features are disclosed in U.S. Pat. Nos. 6,189,867; 5,927,438; and 5,868,380, which are herein incorporated by reference.
Some pulleys also include cord extensions for releasing the load. With such pulleys, the user typically has to raise the load slightly with the pulley system to take pressure off a toothed cam before the user can completely move the cam out of the way to allow releasing or lowering of the load. For such pulleys, see U.S. Pat. Nos. 5,664,640 and 5,927,438, which are herein incorporated by reference.
While pulleys with locking mechanisms and cord extensions for releasing a load are known in the art, there is a need for a self-camming pulley with an improved locking mechanism and release mechanism for a controllable release under a load.